ONLINE EDUCATION: Although tuition has been increasing, a plethora of free online options has become available. (Photo: Ina Peters/iStockphoto)

Anyone who has paid tuition or sent in checks to repay a student loan knows that education is not cheap. The cost of a college education can easily reach six figures, with some graduates leaving school with a diploma and more than $200,000 in debt.

The costs associated with higher education are climbing even faster than inflation. When you factor in the added costs of books, meal plans and housing, it's enough to make even the most frugal savers cringe.

Luckily, while tuition has been rising, a plethora of free online options has become available. Some websites like the Khan Academy exist to help students round out their understanding of subjects like trigonometry and calculus while top-notch universities have begun to put courses online for free. We can't all get accepted to Harvard, but we can click over and watch every lecture from an Introduction to Computer Science course and do all the assignments and tests like real Harvard students do.

There has never been a better time to flex your brain with free online courses, so we scoured the Web high and low and found some of the best options for increasing your brainpower from the comfort of your computer without paying a dime in tuition. Here are some of the best options to be found. Enjoy!

Khan Academy

Khan Academy was started when founder Salman Khan started making videos to help his cousins with math homework. As he made more videos, he began to attract an audience outside his immediate friends and family. He has since branched out into science, history and economics and he quit his day job as a hedge fund analyst in 2006. He’s created more than 2,600 videos and attracted fans and financial backers like Bill Gates and Google's philanthropic arm.

If you are looking to round out your knowledge of math, science, history or economics, a visit to Khan Academy is good place to start. The website has a great feature that will track your progress and test your comprehension in any given focus, giving you points for your work, just like a video game.

MIT

MIT is consistently ranked as one of the top universities in the world and has produced scores of Nobel Prize winners and Rhodes Scholars, astronauts, famed architects and successful entrepreneurs. The coursework is well known for being fast-paced and challenging, and the institution prepares its graduates to face a hungry sea of tech companies clamoring for their employment post-graduation.

MIT is highly selective and tuition and expenses will set you back around $50,000 per year. If you don't have the grades, availability or cash to shell out for a proper MIT education, you can click over to the MIT OpenCourseWare site and dive right into whatever class you'd like. The school has put nearly all of its courses online and also makes homework and tests available for virtual students. The school spends millions of dollars every year on the effort and can be credited with spurring other colleges like Harvard and Stanford into doing the same with their coursework.

University of Reddit

The University of Reddit is an offshoot of the popular link-sharing website Reddit and was founded by people dedicated to the idea of setting information and education free. Classes are taken and taught by anyone and cover a variety of topics, including drawing, introduction to filmmaking, beginning computer programming with java, puppy training, how to speak Korean and Arabic, and how to play the (notoriously difficult) video game Dwarf Fortress. Since the University of Reddit is open to anyone who wants to teach a course, quality can be spotty, but it's easy to view each lesson to find the best material. The class formats make it easy to learn at your own pace.

Stanford

Stanford University, one of the top technology schools in the world, was founded in 1891 as a West Coast answer to Harvard. The university has deep ties in the world of technology and was an early booster of Silicon Valley. It counts as its alumni founders of companies like Google, Yahoo!, Sun Microsystems and Hewlett-Packard. Stanford has been making many of its courses available online since 2006 and has a large presence on iTunes where you can download free lectures in subjects like business, engineering, history, math, science and education.

Harvard

Harvard University is perhaps the best-known top-tier school in the world and was established in 1636, making it the oldest university in the United States. It's also the richest school in the world with an endowment in the tens of billions of dollars. This wealth allows Harvard students with parents making less than $60,000 a year to pay no in tuition, and those making up to $80,000 a year pay just a few thousand dollars. That money has also allowed the university to make its online courses free to the world. Visitors to the Harvard Extension School can take eight online courses in their entirety.

Berkeley

The University of California, Berkeley is another top school that has invested in putting its coursework online for free. The university was founded in 1866 and is one of the top-ranked schools in the world with a widely respected standing in research and technology. The institution has been affiliated with the Los Alamos National Laboratory, Lawrence Livermore National Laboratory and the Lawrence Berkeley National Laboratory, and its alumni have been credited with discovering 16 elements on the Periodic Table of Elements. Berkeley's online offerings cover many of the school’s courses and are recorded as videos on YouTube.

Yale

Yale University is the third-oldest university in the United States and was founded in 1701. Yale is another extremely rich school with a total endowment of nearly $20 billion. Yale has churned out five U.S. presidents, 19 U.S. Supreme Court justices and countless business, political and academic leaders. And now, thanks to the school’s Open Yale Courses, many of the school’s introductory level classes are available to anyone with a Web browser. Courses are available in departments like English, astronomy, music, political science, environmental studies and more, andthey are available via video, audio or transcript.